STORAGE PHOSPHOR DIRECT MAGNIFICATION MAMMOGRAPHY IN COMPARISON WITH CONVENTIONAL SCREEN-FILM MAMMOGRAPHY - A PHANTOM STUDY

Contact mammography with current photostimulable storage phosphors is hampered by its low spatial resolution. Detail visualization can be im proved by geometric magnification radiography which enlarges small det ails to exceed inherent image noise. This study compares storage phosp hor mammography using a dedicated direct magnification system with sta te-of-the-art conventional screen-film mammography. Storage phosphor d irect magnification survey views (1.7 x) and spot views (4 x) were obt ained with a prototype mammography unit providing focal spot sizes of 120-40 mu m. Conventional technique screen-him survey views(1.1 x) and spot views (1.8 x) served as comparison. A contrast detail study and a receiver operating characteristic (ROC) analysis using an anthropomo rphic breast phantom with superimposed microcalcifications was perform ed. Contrast detail resolution in the digital and conventional survey views were equivalent. For the spot views, contrast detail resolution was significantly higher with the digital technique (p<0.001). ROC ana lysis of 400 observations demonstrated a significantly higher performa nce (p<0.001) with digital images versus conventional screen-film mamm ograms. The area under the ROC curve (A,) in the digital survey views was 0.76+/-0.07 versus 0.59+/-0.02 in the conventional technique. In d igital spot views, A(Z) was 0.82+/-0.07 as compared with 0.66+/-0.04 i n the conventional spot views. These results suggest that storage phos phor digital mammography in conjunction with direct geometric magnific ation technique may be superior to conventional screen-film mammograph y in the detection of microcalcifications.